%% You should probably cite rfc8201 instead of this I-D.
@techreport{ietf-6man-rfc1981bis-04,
    number =    {draft-ietf-6man-rfc1981bis-04},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-ietf-6man-rfc1981bis/04/},
    author =    {Jack McCann \textless{}\textgreater{} and Stephen E. Deering \textless{}\textgreater{} and Jeffrey Mogul \textless{}\textgreater{} and Bob Hinden},
    title =     {{Path MTU Discovery for IP version 6}},
    pagetotal = 17,
    year =      2017,
    month =     jan,
    day =       31,
    abstract =  {This document describes Path MTU Discovery for IP version 6. It is largely derived from RFC 1191, which describes Path MTU Discovery for IP version 4. It obsoletes RFC1981.},
}